Particle size effects, such as optical functions, surface-modification functions, thermal properties, and so forth, appear when a metal is microfine-sized to the nanosize level, and it is therefore expected that polymer composites that incorporate such metal particles will behave as functional materials. Structures comprising metal microparticles dispersed in a polymer matrix are in fact known, and the dispersion of metal nanoparticles in a crosslinked polymer and particularly a silicone-type polymer is known for the purpose of obtaining a photofunctional material or imparting electroconductivity (for example, Patent References 1 to 3). However, achieving a uniform dispersion of the metal nanoparticles in the polymer matrix is problematic in the cited methods, and the polymer functionality anticipated for metal nanoparticle incorporation has yet to be satisfactorily achieved. In addition, uniform metal nanoparticles are very unstable during handling because they readily aggregate during handling with a distinct tendency to form large particles. Due to a high reactivity, they are also prone to problems such as outscattering and oxidation when simply handled in air. This has made it difficult to produce uniform metal nanoparticles on an industrial basis, and the facile mass production of structures comprising metal microparticles dispersed in a polymer matrix without the use of special production facilities has been quite problematic, particularly with regard to industrial manufacturing processes.
Surface treatment and electroless plating methods are also known in which an article or particulate having SiH-functional polysiloxane at the surface is treated with, for example, an aqueous solution containing a metal cation, thereby reducing the metal cation at the surface of the particulate or article and coating the particulate or article with a surface metal film (for example, Patent References 4 to 9). However, in these surface-treatment technologies, the post-reduction metal forms a coating layer in which the metal atoms are disposed in the form of a layer over the treated surface as a whole, and as a consequence the particle effects expected for metal nanoparticles, i.e., various functions such as optical functions, surface-modification functions, thermal properties, and so forth, are lost.
Patent Reference 10, on the other hand, describes the precipitation and separation of metal by the reduction of a metal compound in organic solvent or aqueous solution using a reducing agent. Organic solvent-soluble crosslinked polysiloxane particles that include this metal are also described. It is also taught that the metal compound can be reduced by the silicon hydride bond. However, this Patent Reference 10 teaches the formation of metal nanoparticles on the surface of the crosslinked polysiloxane after its production and describes neither a structure in which stable metal nanoparticles are dispersed in a crosslinked polymer matrix nor the formation of a structure in which metal nanoparticles are stably incorporated in a polymer matrix.
Patent References:    [Patent Reference 1] JP 2001-316501 A (JP 3,517,698 B)    [Patent Reference 2] JP (PCT) 2001-527108 A    [Patent Reference 3] JP 02-051535 A (JP 04-077401 B)    [Patent Reference 4] JP 01-115957 A (JP 2,686,750 B)    [Patent Reference 5] JP 2000-073176 A    [Patent Reference 6] JP 64-062475 A    [Patent Reference 7] JP 2002-004057 A (JP 3,536,788 B)    [Patent Reference 8] JP 2001-152045 A (JP 3,716,903 B)    [Patent Reference 9] JP 11-271981 A (JP 3,440,815 B)    [Patent Reference 10] JP 10-219112 A (JP 2,956,030 B)